Afraid the entire panel has to come out. Nothing too technical about it, but there are a lot of hidden screws and clips, so be patient.
The Haynes manual will show you how, or check a few websites (copy and paste urls)
http://www.corsa-c.co.uk/forum/showthread.php?t=1121
You have to join to se that one, or
http://www.allcorsa.co.uk/forums/showthread.php/tutorial-request-2642.html?s=15745319fa27492a6c4525dc27023718&
gdd, March 2012
